LECTURE IX. 
The celebrated Cuvier seems to suppose that they 
have not. It is acknowledged indeed that the 
animals of the Crab and Lobster tribe, the Mo- 
noculi, and others of that particular cast, have a 
genuine circulation ; but these animals should, 
according to some Zoologists, be separated from 
insects, and form a distinct division in the animal 
kingdom. Nay Monsieur Lamarck is willing to 
exclude even the Spider tribe from the class of 
insects, because in these animals the heart and 
circulation of the blood are distinctly visible. 
The organ which the famous Italian anatomist 
Malpighi supposed to constitute the heart, or 
rather a kind of chain of hearts, in the Silkworm, 
has been since proved to be a vessel of a different 
nature, the use of which does not appear to be 
fully understood; but no ramifications of blood- 
vessels proceed from it. 
It seems to have escaped the attention of those 
who are not willing to allows a circulation of the blood 
in insects, that, though it may not be perceptible 
in the major part, yet it certainly appears to take 
place in some which are allowed on all hands to 
be genuine insects ; and particularly in the genus 
Cimex or Bug. I shall here give a quotation om 
